The invention relates to a fluid pump and to a method for forming a fluid pump, in particular water pump, with a bearing pin on which an impeller with a plain bearing bush is rotatably mounted.
Fluid pumps, in particular water pumps, are used, for example, in motor vehicles in order to ensure circulation of a coolant. Use is made here of various designs of fluid pumps. Fluid pumps are generally formed in two parts and comprise a pumping region and a motor region. In this case, an impeller can serve as a bladed wheel for the fluid circuit and for the driving of the fluid pump. The impeller is generally formed from a plastoferrite in order to be able to have magnetic properties. The impeller is generally connected to a plain bearing bush which is formed, for example, from a briquet bonded with synthetic resin. As a result, the impeller can be used as a rotor which sits with the plain bearing bush on a bearing pin and rotates about the bearing pin.
Due to the different thermal expansion of the materials of the impeller and the plain bearing bush, cracking frequently occurs due to internal stresses in the components, and this, in turn, may lead to the component failing. Furthermore, the production of the fluid pump is time-consuming, since the plain bearing bush has to be placed in the injection molding die before the impeller can be cast over the plain bearing bush in the injection molding process.